Scheduling method and base station

ABSTRACT

Embodiments of the present disclosure provide a scheduling method and a base station. In a cell handover process, a target base station serving a target cell receives a random access request from a terminal, sends a random access response to the terminal according to the random access request, and proactively sends an uplink grant to the terminal after sending the random access response and prior to receiving a handover complete command from the terminal. By proactively sending the uplink grant, the target base station can perform uplink scheduling for UE before cell handover is completed, so as to reduce an uplink transmission latency caused by the cell handover.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/228,149, filed on Dec. 20, 2018, which is a continuation ofInternational Application No. PCT/CN2016/087029, filed on Jun. 24, 2016.All of the afore-mentioned patent applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

Embodiments of the present disclosure relate to communicationstechnologies, and in particular, to a scheduling method and a basestation.

BACKGROUND

In a wireless communications system, a base station allocates a radioresource to a terminal, to implement data transmission. The radioresource allocation process is also referred to as a scheduling process.Scheduling may include uplink scheduling and downlink scheduling. Uplinkscheduling is used to allocate an uplink resource to the terminal, sothat the terminal sends data on the uplink resource. Downlink schedulingis used to allocate a downlink resource to the terminal, so that thebase station uses the downlink resource to send data to the terminal.

Uplink scheduling may be triggered by a scheduling request (SR) or abuffer status report (BSR). That is, when a terminal needs to senduplink data, the terminal may trigger, by reporting the SR or the BSR, abase station to allocate an uplink resource to the terminal. Forexample, referring to FIG. 1, FIG. 1 is a schematic diagram of anexisting uplink scheduling process. As shown in FIG. 1, in the uplinkscheduling process, when a terminal needs to send uplink data, theterminal sends an SR to a base station to inform the base station thatthe terminal needs to send the uplink data; and after receiving the SR,the base station delivers an uplink grant (UL Grant) to the terminal.The uplink grant indicates a resource allocated to the terminal. Afterreceiving the uplink grant, the terminal sends a BSR by using theresource indicated by the uplink grant, to inform the base station of avolume of the uplink data to be sent by the terminal, so that the basestation allocates more uplink resources to the terminal based on theBSR, and delivers an uplink grant. In this way, the terminal cancontinue transmitting uplink data by using a resource indicated by theuplink grant. In addition, the uplink data may also be sent while theBSR is being sent.

When a serving cell of the terminal changes (for example, handoveroccurs), or the terminal re-accesses the serving cell because of somereasons, the terminal also triggers uplink scheduling by sending an SRor a BSR. For example, when being handed over from a source cell to atarget cell, the terminal reports an SR in the target cell, or sends aBSR when the handover is completed, to trigger uplink scheduling.

It can be learned that, in the prior art, the terminal can triggeruplink scheduling only after handover on the terminal is completed. Arelatively long time is required for cell handover. As a result, anuplink data transmission latency of the terminal is relatively long,thereby affecting user experience. In particular, for a service with arelatively high latency requirement (such as a voice service), suchlatency is even unacceptable.

SUMMARY

Embodiments of the present disclosure provide a scheduling method and abase station, so as to reduce an uplink transmission latency caused bycell handover.

According to a first aspect, this application provides a schedulingmethod, where the method is applied to a process of handing over aterminal to a target cell, and the method includes: receiving, by atarget base station, a random access request sent by the terminal;sending a random access response to the terminal according to the randomaccess request; and proactively sending an uplink grant to the terminalafter sending the random access response and before receiving a handovercomplete command. The target base station is a base station serving thetarget cell. By proactively sending the uplink grant, the target basestation can perform uplink scheduling for UE before cell handover iscompleted, so as to reduce an uplink transmission latency caused by thecell handover.

In one embodiment, when receiving the handover complete command sent bythe terminal, the target base station stops proactively sending theuplink grant to the terminal. By stopping, based on the handovercomplete command, proactively sending the uplink grant, a resource wastecaused because excessive uplink resources are allocated throughproactive granting is reduced, and it can be ensured that an uplinkresource is allocated to the terminal according to an existingscheduling manner after the handover succeeds.

In another embodiment, proactively sending, by the target base station,an uplink grant to the terminal includes: sending, by the target basestation, a plurality of uplink grants to the terminal in a preset timeperiod; and after the preset time period expires, stopping proactivelysending the uplink grants to the terminal.

In yet another embodiment, after starting to proactively send the uplinkgrant, the target base station receives a BSR or an SR sent by theterminal, and stops, based on the BSR or the SR, proactively sending theuplink grant to the terminal. By stopping, based on the BSR or the SR,proactively sending the uplink grant, a resource waste caused becauseexcessive uplink resources are allocated through proactive granting isreduced. In addition, the BSR or the SR is sent when the terminal needsto send uplink data; therefore, a case in which a requirement of theterminal cannot be met because excessive few resources are allocated dueto stop of proactive uplink-grant sending is further avoided.

In still another embodiment, before proactively sending the uplink grantto the terminal, the target base station may further determine whetherthe terminal currently has a voice service, and only when the terminalcurrently has a voice service, the target base station proactively sendsthe uplink grant to the terminal. Determining whether a voice servicecurrently exists can reduce an uplink resource waste caused becauseproactive granting is used for some services whose latency requirementsare not high.

In another embodiment, proactively sending, by the target base station,an uplink grant to the terminal includes: after sending the randomaccess response, increasing, by the target base station, a size of thebuffer status report BSR of the terminal; allocating an uplink resourceto the terminal based on an increased size of the BSR; and thenproactively sending, to the terminal, an uplink grant that is used toindicate the uplink resource.

In one embodiment, increasing, by the target base station, a size of theBSR of the terminal includes: increasing, by the target base station,the size of the BSR of the terminal based on a current service attributeof the terminal; or increasing, by the target base station, the size ofthe BSR based on a preset size. According to the method for increasingthe size of the BSR based on the service attribute, uplink resourceutilization can be improved, a resource waste caused because excessiveuplink resources are allocated can be reduced, and a case in which arequirement of the terminal cannot be met because excessive few uplinkresources are allocated can further be avoided.

In one embodiment, proactively sending, by the target base station, anuplink grant to the terminal includes: periodically and proactivelysending, by the target base station, an uplink grant of a preset size tothe terminal.

In another embodiment, proactively sending, by the target base station,an uplink grant to the terminal after sending the random access responseand before receiving a handover complete command includes: starting, bythe target base station, to send the uplink grant to the terminal froman N^(th) TTI that is after the random access response is sent, where Nis a positive integer greater than or equal to 3 and less than or equalto 10.

In one embodiment, the target base station starts to send a plurality ofuplink grants to the terminal from the N^(th) transmission time intervalTTI that is after the random access response is sent.

According to a second aspect, this application provides a base station,where the base station includes function modules or means for performingthe method provided in any one of the first aspect and the embodimentsof the first aspect.

According to a third aspect, this application provides a base station,where the base station includes a processor and a memory, the memory isconfigured to store a program, and the processor invokes the programstored in the memory, so as to perform the method provided in the firstaspect of this application.

In the foregoing aspects, the target base station proactively sends theuplink grant to the terminal after sending the random access responseand before receiving the handover complete command. By proactivelysending the uplink grant, the target base station can perform uplinkscheduling for UE before cell handover is completed, so as to reduce anuplink transmission latency caused by the cell handover.

BRIEF DESCRIPTION OF DRAWINGS

To describe the technical solutions in the embodiments of the presentdisclosure or in the prior art more clearly, the following brieflydescribes the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show some embodiments of the presentdisclosure, and persons of ordinary skill in the art may derive otherdrawings from these accompanying drawings without creative efforts.

FIG. 1 is a schematic diagram of an existing uplink scheduling process;

FIG. 2 is a schematic diagram of uplink scheduling in an existing cellhandover process;

FIG. 3 is a time sequence diagram of an uplink scheduling process shownin FIG. 2;

FIG. 4 is a schematic diagram of uplink scheduling in a cell handoverprocess according to one embodiment;

FIG. 5 is a flowchart of a scheduling method according to oneembodiment;

FIG. 6 is a time sequence diagram of an uplink scheduling processaccording to one embodiment;

FIG. 7 is a schematic structural diagram of a base station according toone embodiment; and

FIG. 8 is a schematic structural diagram of another base stationaccording to one embodiment.

DESCRIPTION OF EMBODIMENTS

To make the objectives, technical solutions, and advantages of theembodiments of the present disclosure clearer, the following clearlydescribes the technical solutions in the embodiments of the presentdisclosure with reference to the accompanying drawings in theembodiments of the present disclosure. Apparently, the describedembodiments are some rather than all of the embodiments of the presentdisclosure. All other embodiments obtained by persons of ordinary skillin the art based on the embodiments of the present disclosure withoutcreative efforts shall fall within the protection scope of the presentdisclosure.

The following describes some terms in this application for ease ofunderstanding by persons skilled in the art.

(1) A terminal, also referred to as user equipment (UE), is a deviceproviding voice and/or data connectivity to a user, such as a handhelddevice or an in-vehicle device with a wireless connection function. Forexample, a common terminal includes a mobile phone, a tablet computer, anotebook computer, a palmtop computer, a mobile internet device (MID),or a wearable device such as a smartwatch, a smart band, or a pedometer.

(2) A radio access network (RAN) device is a device that connects aterminal to a wireless network and is also referred to as a basestation. The radio access network device includes but is not limited to:an evolved NodeB (eNB), a radio network controller (RNC), a NodeB (NB),a base station controller (BSC), a base transceiver station (BTS), ahome evolved NodeB or a home NodeB (for example, Home evolved NodeB, orHome Node B, HNB), or a baseband unit (BBU). In addition, the radioaccess network device may include a wireless-fidelity (Wifi) accesspoint (AP), or the like.

(3) “A plurality of” means two or more than two. “And/or” describes anassociation relationship of associated objects and represents that threerelationships may exist. For example, A and/or B may represent any ofthe following three cases: Only A exists, both A and B exist, or only Bexists. The character “/” generally indicates an “or” relationshipbetween the associated objects before and after the character.

Referring to FIG. 2, FIG. 2 is a schematic diagram of uplink schedulingin an existing cell handover process. As shown in FIG. 2, when aterminal needs to be handed over from a source cell to a target cell, abase station serving the source cell (referred to as a source basestation below) sends a handover command (HO-CMD) to the terminal. Afterreceiving the handover command, the terminal sends a random accessrequest to a base station serving the target cell (referred to as atarget base station below). The target base station sends a randomaccess response (RAR) to the terminal according to the random accessrequest. Then, the terminal sends a handover complete command (HO-CMP)to the target base station. The handover complete command may carry abuffer status report (BSR). After receiving the handover completecommand, the target base station discovers the BSR carried in thehandover complete command, and learns that the terminal needs to senduplink data; therefore, the target base station allocates an uplinkresource to the terminal based on the BSR, and sends an uplink grant tothe terminal, to indicate the uplink resource allocated to the terminal.Subsequently, the terminal can use the uplink resource indicated by theuplink grant to send the uplink data to the target base station.

It can be learned that, the terminal can trigger uplink scheduling onlyafter handover on the terminal is completed. A relatively long time isrequired for cell handover. As a result, a specific uplink datatransmission latency of the terminal is caused, thereby affecting userexperience. In particular, for a latency-sensitive service such as avoice service, such latency is even unacceptable.

Referring to FIG. 3, FIG. 3 is a time sequence diagram of an uplinkscheduling process shown in FIG. 2. In FIG. 3, a Long Term Evolution(LTE) system is used as an example. As shown in FIG. 3, a first rowrepresents time, and a unit is a transmission time interval (TTI); asecond row represents actions of a target base station; and a third rowrepresents actions of a terminal. It is assumed that the target basestation sends a random access response to the terminal in a TTI 0, theterminal sends a handover complete command to the target base station ina TTI 6, and the target base station receives the handover completecommand in a TTI 9 and starts to send an uplink grant from a TTI 10. Ifthere is a relatively large amount of data to be sent by the terminal,the base station may send uplink grants to the terminal for a pluralityof times, for example, uplink grants are sent in all of TTIs 10 to 13.It should be noted that, a time in which the target base stationreceives the handover complete command is not fixed but may be a TTI 8,the TTI 9, or the TTI 10. Correspondingly, when the time in which thetarget base station receives the handover complete command is the TTI 8,a time in which the target base station starts to send the uplink grantto the terminal may be the TTI 9, or when the time in which the targetbase station receives the handover complete command is the TTI 10, thetarget base station may start to send the uplink grant to the terminalin the TTI 11. It may be learned from the foregoing time sequencerelationship that, from sending the random access response to startingto send the uplink grant, the target base station needs a time of atleast 8 to 10 TTIs. Therefore, for a latency-sensitive service such as avoice service, user experience is severely affected.

To reduce an uplink data transmission latency, an embodiment of thepresent disclosure provides a scheduling method. In a cell handoverprocess, after sending a random access response and before receiving ahandover complete command, a target base station proactively sends anuplink grant to a terminal. By proactively sending the uplink grant, thetarget base station can perform uplink scheduling for UE before cellhandover is completed, so as to reduce a latency caused by the cellhandover. The following describes the method in the present disclosurein detail by using specific embodiments.

In addition, it should be noted that, when the foregoing handover isinter-cell handover, a source cell and a target cell are differentcells, and the source cell and the target cell may be served by a samebase station or may be served by different base stations. In otherwords, a source base station and a target base station may be a samebase station or may be different base stations. When the foregoinghandover is intra-cell handover, a source cell and a target cell may bea same cell, and a target base station is a source base station.

Referring to FIG. 4, FIG. 4 is a schematic diagram of uplink schedulingin a cell handover process according to one embodiment. As shown in FIG.4, a difference between FIG. 4 and FIG. 2 lies in that, after sending arandom access response and before receiving a handover complete command,a target base station proactively sends an uplink grant to a terminal.In addition, the target base station may consecutively send uplinkgrants for a plurality of times, or may send an uplink grant for onlyonce.

FIG. 5 is a flowchart of a scheduling method according to oneembodiment. The method is applied to a process of handing over aterminal to a target cell. As shown in FIG. 5, the method in thisembodiment may include the following operations:

Operation 101. A target base station serving the target cell receives arandom access request sent by the terminal.

Operation 102. The target base station sends a random access response tothe terminal according to the random access request.

Operation 103. The target base station proactively sends an uplink grantto the terminal after sending the random access response and beforereceiving a handover complete command.

In operation 103, the target base station proactively sends the uplinkgrant to the terminal after sending the random access response andbefore receiving the handover complete command.

Herein, proactive sending means that the target base station sends theuplink grant to the terminal when the target base station does notreceive an SR or a BSR sent by the terminal. An existing uplinkscheduling procedure is as follows: After cell handover is completed,when a terminal needs to send uplink data, the terminal adds a BSR to ahandover complete command sent to a target base station, and afterreceiving the handover complete command, the target base stationallocates a resource to the terminal based on the BSR, and delivers anuplink grant. Alternatively, after a target base station receives ahandover complete command sent by a terminal, the terminal sends an SRto the target base station. Usually, the SR is used to inform the targetbase station only that the terminal needs to send data but does not beused to inform the target base station of a specific volume of data thatneeds to be sent by the terminal. The target base station allocates aresource to the terminal based on the SR, and delivers an uplink grant.In this case, because the target base station does not know a specificquantity of uplink resources that are needed by the terminal, the targetbase station may allocate, to the terminal, only an uplink resource thatis used to send the BSR, and the terminal sends the BSR on the uplinkresource that is granted. The BSR carries a volume of data that needs tobe sent by the terminal, and the target base station provides the grantto the terminal based on the BSR. After obtaining the uplink grant, theterminal may alternatively add the BSR to an uplink subframe if theterminal further needs to send data subsequently. The target basestation continues providing a grant to the terminal based on the BSR.Certainly, the target base station may alternatively allocate a resourceof a preset size to the terminal after receiving the SR, and theterminal uses the resource to send the BSR, and in addition, uses a restportion of the resource to send the uplink data. In the solution of thisembodiment, when the terminal has not been handed over to the targetbase station yet, the terminal cannot send the SR or the BSR to thetarget base station. In this case, the terminal may need to transmitdata. To ensure that the data of the terminal can be transmitted intime, the target base station sends the uplink grant to the terminaleven if the target base station does not receive the SR or the BSR.

The target base station may send the uplink grant in any time aftersending the random access response and before receiving the handovercomplete command. In an existing network system, such as a UniversalMobile Telecommunications System (UMTS) or an LTE system, a TTI isusually used as a basic unit of time that is managed in radio resourcemanagement (for example, scheduling), and one TTI is one millisecond(ms), that is, a length of a subframe. Certainly, with evolution oftechnologies, a length of the TTI may be another value, for example, 0.5ms. This is not used to limit the present disclosure. The target basestation may start to proactively send the uplink grant to the terminalfrom an N^(th) TTI that is after the random access response is sent. Nis a positive integer greater than or equal to 3 and less than or equalto 10. When a time in which the target base station receives thehandover complete command is a TTI 8, a maximum value of N is 8; when atime in which the target base station receives the handover completecommand is a TTI 9, a maximum value of N is 9; or when a time in whichthe target base station receives the handover complete command is a TTI10, a maximum value of N is 10.

In this embodiment, a quantity of uplink grants that are proactivelysent by the target base station is not limited. The target base stationmay start to send one uplink grant or a plurality of uplink grants fromthe N^(th) TTI that is after the random access response is sent. Duringsending of the plurality of uplink grants, the uplink grants may beconsecutively or inconsecutively sent. That is, the target base stationmay start to consecutively send the uplink grants from the N^(th) TTIthat is after the random access response is sent, or may start toinconsecutively send the uplink grants from the N^(th) TTI that is afterthe random access response is sent. For example, the target base stationsends one uplink grant every other TTI or sends one uplink grant everyother two TTIs. A value of N may be preset, or may be determined in realtime by the target base station according to a preset rule. Fordifferent services of the terminal, values of N may be the same or maybe different. The value of N may be determined based on latencysensitivity of a service. The value of N for a latency-sensitive servicemay be less than that for a latency-insensitive service. For example,for the latency-sensitive service, the value of N is 3, and for thelatency-insensitive service, the value of N may be 6.

When the value of N is 3, the target base station starts to proactivelysend the uplink grant to the terminal from a third TTI that is after therandom access response is sent. FIG. 6 is a time sequence diagram of anuplink scheduling process according to one embodiment. As shown in FIG.6, it is assumed that a target base station sends a random accessresponse in a TTI 0, the target base station starts to send an uplinkgrant from a TTI 3, a terminal sends a handover complete command to thetarget base station in a TTI 6, and the target base station receives thehandover complete command in a TTI 9. According to a mechanism in theforegoing embodiment, the target base station starts to send the uplinkgrant from the TTI 3, and the terminal starts to perform physical uplinkshared channel (PUSCH) transmission at an interval of four TTIs, thatis, the terminal starts to perform the PUSCH transmission from a TTI 7.By comparing FIG. 2 and FIG. 6, it can be learned that, in the method inthis embodiment, the target base station starts to send the uplink grantfrom the TTI 3. Compared with the prior art in which a target basestation can start to send an uplink grant as early as in a TTI 10, alatency decreases from nine TTIs to three TTIs, that is, the latencydecreases by six TTIs.

There may be a plurality of embodiments in which the target base stationproactively sends the uplink grant to the terminal. For example, thetarget base station periodically and proactively sends an uplink grantof a preset size to the terminal; for another example, the target basestation proactively increases a size of a BSR of the terminal, andtriggers the uplink grant based on the increased size of the BSR. Thesize of the BSR is maintained as a buffer size value (BS value) in thebase station and the terminal. The terminal reports an index to the basestation based on a size of a BSR of the terminal. The index is used toindicate the size of the BSR. After receiving the index, the basestation updates a size of a BSR that is maintained by the base station,allocates an uplink resource to the terminal based on an updated size ofthe BSR, and delivers a grant. In this embodiment of this application,the target base station increases the size of the BSR by itself,triggers uplink resource allocation for the terminal, and delivers thegrant. In a process of increasing the size of the BSR, the size of theBSR may be automatically and periodically increased or may be increasedall at a time based on a preset size, or may be increased based on aservice attribute of the terminal. For example, when a current serviceof the terminal is a voice service, a voice packet size may beestimated, and the size of the BSR may be proactively increased based onthe voice packet size.

According to the method for increasing the size of the BSR based on theservice attribute, uplink resource utilization can be improved, aresource waste caused because excessive uplink resources are allocatedcan be reduced, and a case in which a requirement of the terminal cannotbe met because excessive few uplink resources are allocated can furtherbe avoided.

In the foregoing method, the target base station determines, based onthe current service attribute of the terminal, a quantity of uplinkgrants that are to be sent. For example, the service attribute is alatency attribute. For a latency-sensitive service, to minimize alatency, the target base station may choose to ensure the latency at acost of wasting some uplink resources; therefore, a value of M isrelatively large, and correspondingly, a value of a quantity L of uplinkgrants allocated by the target base station is also large. For alatency-insensitive service, to avoid an uplink resource waste, a valueof M is relatively small, and correspondingly, a value of a quantity Lof uplink grants allocated by the target base station is also small. Theservice attribute may alternatively be a service data type, and theservice data type includes types such as text, image, video, and audio.For a video service and an audio service, to improve user experience,values of M and L are relatively large. For a text or an image, to avoidan uplink resource waste, values of M and L are relatively small. Theforegoing are merely examples for description, the service attribute isnot limited to the latency attribute and the data type, and may furtherbe another attribute.

In this embodiment, the target base station proactively sends the uplinkgrant before receiving the handover complete command and still performsscheduling in an existing uplink scheduling manner after receiving thehandover complete command. The target base station may stop proactivelysending the uplink grant in the following cases:

(1) The target base station receives the handover complete command sentby the terminal, and stops, based on the handover complete command,proactively sending the uplink grant to the terminal.

(2) The target base station sends a plurality of uplink grants to theterminal in a preset time period, and after the time period expires, thetarget base station stops proactively sending the uplink grants to theterminal. The preset time period may be a plurality of TTIs, in theplurality of TTIs, the target base station proactively sends the uplinkgrants to the terminal, and when the plurality of TTIs end, the targetbase station stops proactively sending the uplink grants to theterminal.

(3) The target base station receives a BSR or an SR sent by theterminal, and stops, based on the BSR or the SR, proactively sending theuplink grant to the terminal. That the terminal sends the SR to thetarget base station indicates that the terminal has been handed over tothe target cell and needs to send data. In this case, scheduling may beperformed based on the existing uplink scheduling manner. Therefore, thetarget base station stops proactively sending the uplink grant to theterminal. Alternatively, the terminal adds a BSR to the handovercomplete command, and the target base station stops, based on the BSRcarried in the handover complete command, proactively sending the uplinkgrant to the terminal. Alternatively, after the target base stationproactively sends the uplink grant, the terminal sends a BSR on agranted uplink resource, and the target base station stops, based on theBSR, proactively sending the uplink grant to the terminal.

The method in this embodiment may be applied to various services, suchas a voice service, a video service, and a text service. The voiceservice is a latency-sensitive service, and a latency that is caused bycell handover causes blocking of uplink voice packets of the terminal.As a result, a specific packet latency is caused, call qualitytemporarily deteriorates, and voice user experience is affected. In oneembodiment, before operation 103, the target base station may furtherdetermine whether the terminal currently has a voice service, and whenthe terminal currently has a voice service, the target base stationproactively sends the uplink grant to the terminal after sending therandom access response and before receiving the handover completecommand. When the terminal currently does not have a voice service, thetarget base station starts to perform scheduling for the terminal afterthe terminal is handed over to the target cell.

It should be noted that the voice service in this embodiment is acollective name for a type of services. The type of services have a samequality of service (QoS) requirement, and the QoS requirement may berepresented by using a QoS class identifier (QCI). The target basestation may determine, based on the QCI, whether the terminal currentlyhas a voice service to be transmitted. For example, a QCI 1, a QCI 2,and a QCI 5 are all voice-related QCIs. The QCI 1 bears a voice service,the QCI 2 bears a video service, and the QCI 5 bears Session InitiationProtocol (SIP) singling of the voice service, such as SIP signaling usedto establish or release the voice service. When the voice service isbeing established, the SIP signaling is sent to a core network device byusing the QCI 5, so that the core network device is triggered toestablish a QCI 1 bearer to establish the voice service, or a QCI 1bearer and a QCI 2 bearer need to be established to implement avideophone service. When the voice service ends, corresponding SIPsignaling is transmitted on the QCI 5, to trigger the CN device torelease the QCI 1 to end the voice service; or for the videophoneservice, the CN device is triggered to release the QCI 1 and the QCI 2,and it is considered that a call ends. Therefore, during determining, bythe target base station, whether the terminal is performing the voiceservice, whether the voice service starts and ends may be determined byusing the SIP signaling transmitted on the QCI 5, or may be determinedby using the QCI 1 bearer.

In this embodiment, in the cell handover process, the target basestation serving the target cell receives the random access request sentby the terminal, sends the random access response to the terminalaccording to the random access request, and proactively sends the uplinkgrant to the terminal after sending the random access response andbefore receiving the handover complete command. By proactively sendingthe uplink grant, the target base station can perform uplink schedulingfor UE before cell handover is completed, so as to reduce an uplinktransmission latency caused by the cell handover.

FIG. 7 is a schematic structural diagram of a base station according toone embodiment. The base station is a target base station serving atarget cell to which a terminal is handed over. As shown in FIG. 7, thebase station includes a receiving module 11, a sending module 12, and ascheduling module 13.

The receiving module 11 is configured to receive a random access requestsent by the terminal.

The sending module 12 is configured to send a random access response tothe terminal according to the random access request.

The scheduling module 13 is configured to: after the sending module 12sends the random access response and before the receiving module 11receives a handover complete command, proactively send an uplink grantto the terminal though the sending module 12.

In one embodiment, the scheduling module 13 is further configured to:when the receiving module 11 receives the handover complete command sentby the terminal, control the sending module 12 to stop proactivelysending the uplink grant to the terminal.

In one embodiment, the scheduling module 13 is configured to: send aplurality of uplink grants to the terminal in a preset time periodthrough the sending module 12; and control the sending module 12 tostop, after the preset time period expires, proactively sending theuplink grants to the terminal.

In one embodiment, the receiving module 11 is further configured toreceive a BSR or an SR sent by the terminal. Correspondingly, thescheduling module 13 is further configured to control, based on the BSRor the SR, the sending module 12 to stop proactively sending the uplinkgrant to the terminal.

In one embodiment, the base station further includes a determiningmodule (not shown in FIG. 7). The determining module is configured todetermine whether the terminal currently has a voice service. In oneembodiment, the scheduling module 13 is configured to:

when the terminal currently has a voice service, after the sendingmodule 12 sends the random access response and before the receivingmodule 11 receives the handover complete command, proactively send theuplink grant to the terminal through the sending module 12.

In one embodiment, the scheduling module 13 proactively sends the uplinkgrant to the terminal in the following manners:

After the sending module 12 sends the random access response, a size ofthe BSR of the terminal is increased; an uplink resource is allocated tothe terminal based on an increased size of the BSR; and an uplink grantthat is used to indicate the uplink resource is proactively sent to theterminal through the sending module 12. In one embodiment, thescheduling module increases the size of the BSR of the terminal based ona current service attribute of the terminal; or increases the size ofthe BSR based on a preset size.

Alternatively, an uplink grant of a preset size is periodically andproactively sent to the terminal.

Alternatively, the uplink grant starts to be sent to the terminalthrough the sending module 12 from an N^(th) TTI that is after thesending module 12 sends the random access response. N is a positiveinteger greater than or equal to 3 and less than or equal to 10. In oneembodiment, the scheduling module starts to send a plurality of uplinkgrants to the terminal from the N^(th) TTI through the sending module12.

The base station shown in FIG. 7 may be configured to perform the methodprovided in the foregoing method embodiment. Specific embodiments andtechnical effects are similar to those of the method provided in theforegoing method embodiment, and details are not described herein again.

It should be noted that the foregoing division of modules of the basestation is merely logical function division, and during actualimplementation, some or all of the modules may be integrated into onephysical entity, or the modules may be physically separated. Inaddition, all the modules may be implemented by invoking software by aprocessing element; or all the modules may be implemented by hardware;or some modules may be implemented by invoking software by a processingelement, and some modules may be implemented by hardware. For example,the scheduling module may be an independently disposed processingelement, or may be integrated into a chip of the base station forimplementation. In addition, the scheduling module may alternatively bestored in a memory of the base station in a form of program code, and isinvoked by a processing element of the base station, to execute theforegoing functions of the scheduling module. Implementation of othermodules is similar to that of the scheduling module. In addition, all orsome of the modules may be integrated, or may be implementedindependently. Herein, the processing element may be an integratedcircuit with a signal processing capability. During implementation, theoperations of the foregoing methods or the foregoing modules may beimplemented by using an integrated logic circuit of hardware in theprocessor element, or by using a software instruction.

For example, the foregoing modules may be configured as one or moreintegrated circuits that implement the foregoing methods, such as one ormore application-specific integrated circuits (ASIC), one or moremicroprocessors (digital signal processor, DSP), or one or more fieldprogrammable gate arrays (FPGA). For another example, when one of theforegoing modules is implemented by invoking program code by aprocessing element, the processing element may be a general purposeprocessor, such as a central processing unit (CPU), or another processorthat can invoke program code. For still another example, the modules maybe integrated together and implemented in a system-on-a-chip (SOC) form.

FIG. 8 is a schematic structural diagram of another base stationaccording to one embodiment. As shown in FIG. 8, the base station inthis embodiment includes an antenna 110, a radio frequency apparatus120, and a baseband apparatus 130. The antenna 110 is connected to theradio frequency apparatus 120. In an uplink direction, the radiofrequency apparatus 120 receives, through the antenna 110, informationsent by a terminal, and sends the information sent by the terminal tothe baseband apparatus 130 for processing. In a downlink direction, thebaseband apparatus 130 processes information to be sent to the terminal,and sends processed information to the radio frequency apparatus 120.After processing the information to be sent to the terminal, the radiofrequency apparatus 120 sends processed information to the terminalthrough the antenna 110.

The method provided in the foregoing embodiment may be implemented inthe baseband apparatus 130. The baseband apparatus 130 includes aprocessing element 131 and a storage element 132. For example, thebaseband apparatus 130 may include at least one baseband processingboard. A plurality of chips are disposed on the baseband processingboard. As shown in FIG. 8, for example, one of the chips is theprocessing element 131 and is connected to the storage element 132, toinvoke a program in the storage element 132, so as to execute anoperation shown in the foregoing method embodiment. The basebandapparatus 130 may further include an interface 133, configured toexchange information with the radio frequency apparatus 120. Forexample, the interface is a common public radio interface (CPRI).

Herein, the processing element may be one processor, or may be acollective name for a plurality of processing elements. For example, theprocessing element may be a CPU or an ASIC, or may be configured as oneor more integrated circuits that implement the foregoing methods, suchas one or more microprocessors DSPs, or one or more field programmablegate arrays FPGAs. The storage element may be one memory or may be acollective name for a plurality of storage elements.

Finally, it should be noted that the foregoing embodiments are merelyintended for describing the technical solutions of the presentdisclosure, but not for limiting the present disclosure. Although thepresent disclosure is described in detail with reference to theforegoing embodiments, persons of ordinary skill in the art shouldunderstand that they may still make modifications to the technicalsolutions described in the foregoing embodiments or make equivalentreplacements to some or all technical features thereof, withoutdeparting from the scope of the technical solutions of the embodimentsof the present disclosure.

What is claimed is:
 1. A method, comprising: receiving, by a terminal, ahandover command from a source cell, wherein the handover commandnotifies the terminal of a handover from the source cell to a targetcell; sending, by the terminal, a random access request to a basestation serving the target cell; receiving, by the terminal, a randomaccess response from the base station; and sending, by the terminal tothe base station, a handover complete command to the base station,wherein after receiving the random access response and prior to sendingthe handover complete command, the terminal receives at least one uplinkgrant from the base station without sending a scheduling request (SR)and a buffer status report (BSR) for requesting the at least one uplinkgrant.
 2. The method of claim 1, further comprising: sending, by theterminal, a BSR to the base station in the handover complete command oron a granted uplink resource indicated by a uplink grant of the at leastone uplink grant.
 3. The method of claim 1, wherein the terminalcurrently has a voice service.
 4. The method of claim 1, wherein theterminal periodically receives the at least one uplink grant from thebase station.
 5. The method of claim 1, wherein the terminalperiodically receives the at least one uplink grants from an N^(th)transmission time interval (TTI) that is after the random accessresponse is sent, wherein N is a positive integer greater than or equalto 3 and less than or equal to
 10. 6. A device, comprising a processorand a memory that stores a program, which when executed by theprocessor, causes the processor to perform: receiving a handover commandfrom a source cell, wherein the handover command notifies the device ofa handover from the source cell to a target cell; sending a randomaccess request to a base station serving the target cell; receiving arandom access response from the base station; sending, to the basestation, a handover complete command to the base station, wherein afterreceiving the random access response and prior to sending the handovercomplete command, the device receives at least one uplink grant from thebase station without sending a scheduling request (SR) and a bufferstatus report (BSR) for requesting the at least one uplink grant.
 7. Thedevice of claim 6, wherein the program, which when executed by theprocessor, causes the processor to perform: sending a BSR to the basestation in the handover complete command or on a granted uplink resourceindicated by an uplink grant of the at least one uplink grant.
 8. Thedevice of claim 6, wherein the device currently has a voice service. 9.The device of claim 6, wherein the device periodically receives the atleast one uplink grant from the base station.
 10. The device of claim 6,wherein the device periodically receives the at least one uplink grantfrom an N^(th) transmission time interval (TTI) that is after the randomaccess response is sent, wherein N is a positive integer greater than orequal to 3 and less than or equal to
 10. 11. A device, applied to a basestation for serving a target cell to which a terminal is handed over,the device comprising a processor and a memory that stores a program,which when executed by the processor, causes the processor to performoperations, the operations comprising: receiving a random access requestfrom a terminal; sending a random access response to the terminalaccording to the random access request; and after sending the randomaccess response and prior to receiving a handover complete command fromthe terminal, proactively sending at least one uplink grant to theterminal without receiving, from the terminal, a scheduling request (SR)and a buffer status report (BSR) for requesting the at least one uplinkgrant.
 12. The device according to claim 11, wherein the operationsfurther comprise: when receiving the handover complete command from theterminal, stopping proactive sending of an uplink grant to the terminal.13. The device according to claim 11, wherein proactively sending theuplink grant to the terminal comprises: sending a plurality of uplinkgrants to the terminal in a preset time period; and wherein theoperations further comprise: after the preset time period expires,stopping proactive sending of an uplink grant to the terminal.
 14. Thedevice according to claim 11, wherein the operations further comprise:receiving a BSR or an SR from the terminal; and stopping, based on theBSR or the SR, proactive sending of an uplink grant to the terminal. 15.The device according to claim 11, wherein the operations furthercomprise: determining whether the terminal currently has a voiceservice; and in a case that the terminal currently has the voiceservice, proactively sending the at least one uplink grant to theterminal after sending the random access response and prior to receivingthe handover complete command.
 16. The device according to claim 11,wherein proactively sending the at least one uplink grant to theterminal comprises: increasing a size of a BSR of the terminal;allocating an uplink resource to the terminal based on the increasedsize of the BSR; and proactively sending an uplink grant that indicatesthe uplink resource to the terminal.
 17. The device according to claim11, wherein proactively sending the at least one uplink grant to theterminal comprises: periodically and proactively sending the at leastone uplink grant of a preset size to the terminal.
 18. The deviceaccording to claim 11, wherein proactively sending the at least oneuplink grant to the terminal comprises: sending the at least one uplinkgrant to the terminal from an N^(th) transmission time interval (TTI)that is after the random access response is sent, wherein N is apositive integer greater than or equal to 3 and less than or equal to10.